Modding upgrading and tuning the BMW M70 engine!

Modifying and improving: "M70 Modifications"

M70 Modifications Guide

How to modify and upgrade the BMW M70

"Comprehensive guide to tuning the BMW M70 engine!"

Sites like TorqueCars are regularly getting emails requesting information on how to improve the M70 from people wanting to know what are the things tuners are recommending when it comes to M70 power upgrades. So let us look into BMW M70 mods and outline the best modifications on this great engine and point out some potential pitfalls along the way.

The BMW M70 provide a fun base for your project and with carefully picked motorsport enhancements like ECU maps, turbo upgrades and camshafts you will definitely increase your driving fun.

In this article we detail the best approach to M70 tuning and point out the ultimate modifications.

When talking about the greatest parts for your M70 engine, we are going to focus on the parts that give the best power gain for you money.

M70 induction kits

Improving air intake on the M70

You need fuel and air for an engine to work. If there is a lack of fuel then it will run lean, if there is insufficient air it runs rich resulting in lost power and potentially damaging the engine. We'll pick up on fuelling later in this article but for now we shall look at air supply.

So the goal to any engine upgrade project to push air and fuel into each cylinder but this has a knock on effect with the air flow sensor.

You'll commonly see there's a restriction in the air flow sensor MAP/MAF/AFM on the M70 when a lot more air is being pulled into the engine.

We see 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor limited torque at a much lower level.

Headers flow the during the engines suck phase from the filter and allow it to be sucked into the engine and mixed with fuel.

The shape and flow rate of the air Intake manifold can make a large difference to to fuel atomisation and engine efficiency on the M70.

I usually find air intake manifolds are in dire need of performance upgrades, although some makers provide well optimised air intake manifolds.

Adding a M70 larger valve kit, doing some M70 port enlargement and head flowing will also raise bhp, and more importantly will give you an improved bhp increase on other parts.

M70 performance cam tips.

Each engine responds better to mild camshaft durations than others.

The map and injectors and fuel pump also have an effect on the power gains you'll get.

Longer valve durations can alter the power band and on most engines the exhaust and intake durations do not need to match, although most cams and tuners use matched pairs there are some advantages to extending the intake or exhaust durations.

Altering your M70 camshaft will make a dramatic difference to the engine engines power. Choosing a higher performance camshaft profile raises the engines power accordingly.

NB: Fast road cams usually raise the bhp and torque throughout the rev band, you could drop a little bottom end bhp but the higher rpm power will be lifted.

Race cams, raise the higher rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

For a typical daily driver you should ideally to match your power band to your usage of the car.

I would be surprised if you have found a M70 Motorsport camshaft is a pleasure to live with when driving in heavy traffic.

Stage 1, 2 and 3 mods for the M70

Stage 1 M70 parts:

Fast road camshaft, Intake headers, Panel air filters, Sports exhaust manifold, Drilled & smoothed airbox, Remaps/piggy back ECU.

Stage 2 M70 parts:

Fast road cam, induction kit, Ported and polished head, high flow fuel injectors, fuel pump upgrades, Sports catalyst & performance exhaust.

Stage 3 M70 parts:

Twin charging conversions, Internal engine upgrades (head flowing porting/bigger valves), Adding or Upgrading forced induction (turbo/supercharger), Crank and Piston upgrades to alter compression, Engine balancing & blueprinting, Competition cam.

Review your options and then source your upgrades and set yourself a power target to save yourself from expensive mistakes.

ECU flashing helps release the full potential of all the tuning parts you've done to your M70.

Tuning tips and articles Engine tuning Transmission tuning Care care Intake & exhaust mods Improve handling Forums

You will typically expect to see gains of approximately 20-30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but your mileage will vary depending on the tuning parts you've carried out and the condition of your engine.

Turbo modifications on the M70

To get a turbo working on a NASP engine there is a lot involved, from lowering compression ratio to improved fuel supply and mapping, so we have found a great guide to helpavoid the common pitfalls or end up with an unfinished project because you were not told what you were getting into by doing this on the M70.

The more air you can get into an engine, the more fuel it can burn and uprating the induction with a turbocharger upgrade makes impressive power gains.

If an engine is turbo charged tuning mods are going to net you a larger power gain and you'll see that turbo charged engines are built using uprated components.

There are common areas of failure for every engine, with some being very over engineered and some only just able to handle stock power

Discover these limitations and upgrade to better pistons and crank to handle the power.

It's not unheard of tuners spending a lot of money on turbocharger upgrades on the M70 only to experience the whole thing go up in smoke when it's used in anger.

Bigger upgraded turbochargers commonly suffer a bottom end lag, and little turbochargers spool up more quickly but don't have the peak end torque gains.

Thankfully the market of turbochargers is always improving and we are seeing variable vane turbochargers, allowing the vane profile is altered according to speed to lower lag and increase top end bhp and torque.

Twin scroll turbochargers divert the exhaust gases into two channels and flow these at differently angled vanes in the turbo charger. They also boost the scavenging effect of the engine.

Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large torque gains, although more complex to install. We have this feature on twinchargers if you want to read more.

Tips about fuel supply on the M70

Don't forget to improve the fuel delivery when you are increasing the performance - it makes the car more thirsty. At this point we flag up the need to over specify your injector capacity.

As a rule of thumb add 15% when fitting an injector, this allows for injector deterioration and provides some spare capacity should the engine need more fuel.

Don't forget that different fuel grades will usually require different settings, a high octane fuel will burn more efficiently than lower octane fuel for example. A car will trim fuel supply to keep within the ideal air fuel mix but at the extreme ends you may need to adjust your injector capacity, or the mapping or you'll get flat spots and potential lean or rich fuel issues..

Recommended M70 performance exhaust upgrades

You may need to increase your exhaust system with an upgraded one is if your current exhaust is actually creating a restriction.

On most factory exhausts you'll see the exhaust flow rate is ok even on modest power gains, but on a serious tuning project with a big boost in power you will certainly need to get a better flowing exhaust.

Sports exhausts can help balance the flow of air through the engine.

But if the exhaust pipe is too large, ie: over two and a half inches diameter, you will lose a lot of the flow rate and end up sapping power and torque.

Typically exhaust restrictions are in the emissions filters installed, so adding a better flowing high performance alternative will help avoid this restriction.

Catalyst removal (NB:catalysts reduce harmful engine emissions) is illegal in most countries and regions.

Faults issues and things to look out for on the M70

Like most engines an M70, should have few issues if it gets properly serviced and looked after.

We cannot stress enough the need for oil changes with the correct grade of oil on the M70, failure to do this will exacerbate engine wear, on a tuned M70 this is more important than ever and close attention should be paid to your maintenance schedule.

If you are interested in learning more or getting impartial tuning advice for your M70 why not pop over to the forums at TorqueCars where you can chat about M70 tuning options and read about others projects who may be planning to do similar modifications on their M70.

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